1. Field of the Invention
The present invention relates to laser radar and more particularly to a laser radar system in which speckle tracking is employed to maximize the radar signal in the presence of degradation generated by speckle.
2. Description of the Prior Art
The operation of radar systems in which a beam of electromagnetic radiation is transmitted from a transmitter location to a remote target and reflected to a receiver location is often compromised by limitations inherent in target generated speckle. As a practical matter, the signal to noise ratio of the signal produced by the radiation reflected by the target is relatively poor due to speckle produced by the interaction of a laser beam with a target having a surface that is optically rough. This interaction limits the potential for processing the radar return signal.
Alternate approaches for minimizing the effect of the noise generated by speckle in the return signal include reducing the dimension of the receiver aperture and increasing the divergence of the transmitter so that the illuminating beam is larger than the target. Both of the above approaches have the disadvantage of requiring increased transmitter power to perform the same mission. Current adaptive optic techniques do not address the sample problem, since their objective is to maximize power on a fixed point in the target plane and are not concerned with maintaining a speckle maximum in the receiver aperture.